The long term objective of this program is to develop and characterize cell lines that are resistant to chemotherapeutic agents derived from primary biopsies of patients with a variety of neoplasms. Cells have been cloned using a new method for soft agar cultivation of human tumor cells ("human tumor stem cell assay"). Attempts have been made to establish these clones as continuous cell lines. Concomitantly, work has begun to develop drug resistant mutants from established tumor cell lines that have maintained their tumor specific characteristics. Work is also in progress to increase the plating efficiencies of tumor cells in soft agar. The effects of Epidermal Growth Factor, vitamins, feeder layers of fibroblasts and macrophages, and glucocorticoids, have been evaluated. Finally, the role of stromal cells (fibroblasts and macrophages) in controlling tumor cell growth in vitro is being studied. Macrophage populations have been fractionated and the effect of different fractions on growth of tumor cells evaluated. Purified fractions of these cells are being used to support the growth of tumor cells in continuous culture.